Method of manufacturing a device for screening-off scattered x-rays



9- s. A. LINDSTEDT ET AL 2.178.798

IIETHDD OF MANUFACTURING A DEVICE FOR SCREENENG-OFF SCATTERED X-RAYS Filed May 1, 193'! gig INVENTORJ swnw nonu- "Lmnsrsnr Patented Nov. 7, 1939 Gustav Adolf Lindstedt and Ernst ate-a cm, 7' Stockholm, Sweden, assignors to 'Aktiebolagct Linham, Stockholm, Sweden Application May 1, 1937, Serial No. 140,255 In Sweden May 5, 1936 1 7 Claims.

Our invention relates toa method of manufacturing devices for screening-01f scattered X-rays as are frequently used when taking X-ray photographs.

An object of our invention is to make a screening device of such -a construction, that itneeds not be moved for sweeping out the shadows of the grid during operation in radiography.

A further object of our invention is to facili- 'tate the manufacture of screening devices having extremely thin laminations.

The essential features of our invention will be readily understood by reference to the accompanying drawing in which Fig. 1 is a sectionized view of a portion of a screening device to which our invention is applicable.

Fig. 2 is a plan view of a sheet of a material from which we make the device shown in Fig. 1. Fig. 3 is a sectionized view of a greatly enlarged scale of a portion of the sheet shown in Fig. 2, p

and

Fig. 4 is a front view of a portion of the said sheet at another scale.

Referring to Fig. 1, the device shown thereby consists of strips or laminations I of lead, alternating with layers of paper or like fibrous material 2.

We prefer to make the strips with an extremely small width, for example 0.1 mm. or still smaller. By those means we obtain the advantage, that in operation the screening device will not cast inconvenient shadows on the photographic plate, even when kept stationary during the exposure. Consequently the screening device will not deleteriously affect the quality of the X-ray image.

On the other hand, we reduce as much as possible the width of the strips in order to prevent that the useful beam of primary X-rays will be partly absorbed by the strips, due to the inclination of the primary X-rays, which increaseswith the distance from the centre. A width of a few millimeters or preferably 1.5 mm. is a suitable dimension for devices of this kind. The mutual distance of the strips may then be about 0.2 nmi.

In manufacturing the grid structure shown in Fig. 1, lead strips l and intermediate layers 2 transparent to X-rays may be joined together by means of an agglutinant.

However we have thinness.

Strips of lead having a thickness of f erent thickness.

(01. est-say ting out the strips. 'For example a sheet oflead 10- of the form represented in Fig. 2 and measuring 50 cm. long by 40 cm. wide is lined with a layer of paper and then cut into strips.

The coating of paper may be applied either to one side of the sheet or to both sides. It is at- 15 tached to the lead surface by means of an agglutinant. When covering the lead sheet at either side, the layers of paper may be of equal thickness or, as shown in Fig. 3, they may have a dif- In the example shown in Fig. 20 3 a sheet 3 of lead having a thickness of about 0.1 mm. has applied to one of its sides a sheet of paper 4 having a thickness of 0.07 mm. and to the other side a sheet of paper 5 having a thickness of 0.14 mm. The latter may consist of a double 25 coating of paper consisting of two layers, each of the same thickness as layer 4.

The sheet thus treated may be cut into strips along the lines 6, shown in Figs. 3 and 4, the width 20 being 1.5 mm. e. g. and then these strips are 30 glued together to form a grid.

The coatings 4 and 5 have together the thickness corresponding tothe desired distance between the absorbing laminations of the completed grid. However it is also possible to provide 35 additional insertstrips of a material pervious to X-rays and so obtain the desired thickness of the interspaces. I

By applying coatings of paper or similar material to the lead sheets, the latter are stiifened, 40 even if only one side thereof is coated, to such an extent, that in the manufacture of the laminations it can be handled without any difficulty. The rigidity may still be increased'by pasting together one or more sheets, provided with coat- 45 ings on both sides as shown in Fig. 3 or with a coating of the same total thickness on one side. From the multiple layer obtained thereby strips or rods may be cut having the desired width and these strips or rods may be glued together to form 50 a continuous plate of the form shown in Fig. 1.

The attachment of the layers to the lead sheet and the mutual attachment of the strips to build up the grid screen, is preferably effected by means of a non-hygroscopic agglutinant, which has a 55 consistency such that it is absorbed by the material of the layer, owing to which this material becomes at the same time less sensitive to moisture.

What We claim is:

1. A method of making a grid for screening-off scattered X-rays, comprising the steps of coating a thin sheet of lead with a layer of fibrous material to produce a composite sheet which can be accurately cut, cutting the composite sheet into narrow strips, and assembling the strips side by side to form the grid.

2. A method of making a grid for screening-oil scattered X-rays, comprising the steps of agglutinating a layer of paper to each side of a thin sheet of lead to produce a composite sheet which can be accurately cut, cutting the composite sheet into narrow strips, and uniting the strips with their flat sides together.

3. A method of making an X-ray grid having lead laminations and intermediate laminations.

of X-ray transparent material, comprising the steps of agglutinating to a thin sheet of lead a layer of fibrous material having the thickness of the intermediate laminations to thereby produce a composite sheet which can be accurately cut, cutting the composite'sheet into narrow strips, and assembling the strips in the same relative positions to form the grid.

4. A method of making an X-ray grid having lead laminations and intermediate laminations of X-ray transparent material, comprising the steps of applying to both sides of a thin sheet of lead layers of fibrous material whose total thickness is equal to the thickness of one of the intermediate laminations to thereby produce a composite sheet which can be accurately cut, cutting the composite sheet into narrow strips, and assembling said strips in the same relative positions to form the grid.

5. An X-ray grid comprising a plurality of composite strips arranged side by side, each of said strips comprising a narrow strip of lead provided with a surface coating of fibrous material.

6. An X-ray grid comprising a plurality of composite strips each having a strip portion of lead provided on one side with a coating of fibrous material, and strips of X-ray transparent material between said composite strips.

7. An X-ray grid comprising a plurality of composite strips each having a strip portion of lead provided on one side with a coating of paper having a thickness less than that of one of the lead strip portions, and a strip of X-ray transparent material between adjacent composite strips and having a thickness greater than that of one of the lead strip portions.

GUSTAV ADOLF LINDSTEDT. ERNST HERBERT 6mm. 

